JP2019112698A - Manufacturing method of sintered magnetic and mold for hot press - Google Patents

Abstract

To provide a manufacturing method of an R-Fe-B-based sintered magnetic, capable of easily controlling temperature and time of sintering, and providing strong magnetic force, and a mold for hot press.SOLUTION: The manufacturing method of an R-Fe-B-based sintered magnet includes arranging an R-Fe-B-based porous magnet 4 in a graphite-made mold for hot press 1, compressing the R-Fe-B-based porous magnet 4 loaded (arranged) in an opening 5 of a die 3 by a punch 2 while heating the die 3 to obtain the R-Fe-B-based sintered magnet. The mold for hot press 1 used for the manufacturing method of the R-Fe-B-based sintered magnet has the die 3 and the punch 2, and the die 3 has a C/C composite made ring 6 arranged in an outer side. The die 3 may be made from a C/C composite and the punch 2 may be made from graphite. The die 3 can be downsized compared to the case that a die 3 is constituted by only graphite, and heat capacity can be reduced.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method of manufacturing a sintered magnet and a mold for hot pressing.

R-Fe-B rare earth magnets (R is a rare earth element, Fe is iron, B is boron) representative of high-performance permanent magnets are mainly composed of R ₂ Fe ₁₄ B phase which is a ternary tetragonal compound It has a tissue structure and exhibits excellent magnetic properties. Such R-Fe-B rare earth magnets are roughly classified into sintered magnets and bonded magnets. A sintered magnet is manufactured by sintering and compacting a fine powder (average particle diameter: several micrometers) of an R-Fe-B based magnet alloy with a press. On the other hand, bonded magnets are usually manufactured by compression molding or injection molding a mixture (compound) of R-Fe-B based magnet alloy powder (particle size: for example, about 100 μm) and bonding resin. Ru.

  In the case of a sintered magnet, individual powder particles have magnetic anisotropy because powders with relatively small particle sizes are used. For this reason, when the powder is compacted with a press, an orienting magnetic field is applied to the powder, whereby a green compact in which powder particles are oriented in the direction of the magnetic field is obtained, and a magnet of strong magnetic force is obtained. be able to. This is because by crushing to the minimum unit (single magnetic domain particle size) which is naturally magnetized in the same direction of the magnet, a strong magnetic force can be obtained by applying a magnetic field from the outside and aligning the direction of the magnetic moment. .

  Patent Document 1 describes a method of manufacturing a rare earth sintered magnet. The process of preparing R-Fe-B based rare earth alloy powder having an average particle size of less than 10 μm in order to make the powder particles finer and obtain a stronger magnetic force, and compacting the R-Fe-B based rare earth alloy powder Heat-treating the green compact at a temperature of at least 650 ° C. and less than 1000 ° C. in hydrogen gas, thereby causing a hydrogenation and disproportionation reaction, and in a vacuum or inert atmosphere Heat-treating the green compact at a temperature of at least 650 ° C. and less than 1000 ° C., thereby causing dehydrogenation and recombination reaction, and a method of producing an R-Fe-B based porous magnet comprising: ing. By this method, hydrogen is once absorbed in the R-Fe-B rare earth alloy powder to form a fine powder, and the direction of the magnetic moment is easily aligned.

  In Patent Document 1, the obtained R-Fe-B-based porous magnet is pressurized at a temperature of 600 ° C. or more and less than 900 ° C. to increase the R-Fe-B-based porous magnet to 95% or more of the true density R-Fe-B based magnets can be obtained by densification. It is described that R-Fe-B based porous magnets can be densified to 95% or more of the true density by this process.

WO 2007/135981

  As described above, since it is sintered again after being crushed once to a unit smaller than the single magnetic domain particle size, a sintered magnet of strong magnetic force can be obtained, but the temperature is raised too much at the time of sintering The raw materials melt and the directions of the magnetic moment are separated, and when exposed to high temperature for a long time, the grain boundaries which are not ferromagnetic grow and reduce the magnetic performance.

  In the present invention, it is an object of the present invention to provide a method of manufacturing a R-Fe-B-based sintered magnet capable of easily controlling the temperature and time of sintering and obtaining a strong magnetic force and a mold for hot pressing.

  The manufacturing method of the sintered magnet of the R-Fe-B type | system | group of this invention for solving the said subject is the following content.

(1) A method of manufacturing a sintered R-Fe-B magnet, wherein the porous R-Fe-B magnet is placed in a graphite hot press mold and pressure is applied while heating, and the hot press The mold comprises a die and a punch, said die having a C / C composite ring arranged on the outside.

According to the method for producing a sintered magnet of R-Fe-B system of the present invention, the die has a ring made of C / C composite material. For this reason, compared with the case where a die | dye is comprised only with graphite, a dice | dies can be miniaturized and heat capacity can be made small.
Therefore, the time required for heating and cooling can be shortened, and melting and deterioration of the R-Fe-B based porous magnet can be prevented.
In addition, since the heat capacity of the die is small, it is easy to control, and if heating is stopped, the temperature rise is easily stopped, and it is possible to prevent the R-Fe-B based porous magnet from being overheated.

(2) A method of manufacturing a sintered R-Fe-B magnet, wherein the porous R-Fe-B based magnet is placed in a hot press mold and pressed while being heated, wherein the hot press mold is , C / C composite die and graphite punch.

According to the method of manufacturing a sintered magnet of R-Fe-B system of the present invention, the die is made of C / C composite material. For this reason, compared with the case where a dice | dies is comprised with graphite, a dice | dies can be miniaturized and heat capacity can be made small.
Therefore, the time required for heating and cooling can be shortened, and melting and deterioration of the R-Fe-B based porous magnet can be prevented.
In addition, since the heat capacity of the die is small, it is easy to control, and if heating is stopped, the temperature rise is easily stopped, and it is possible to prevent the R-Fe-B based porous magnet from being overheated.

  Moreover, as for the manufacturing method of the sintered magnet of R-Fe-B system of this invention, it is desirable that it is the following aspect.

(3) The die has a tapered inner surface and has a sleeve formed of a plurality of divided graphite pieces inside.

  If a sleeve is provided inside the die, the sintered magnet can be easily removed by disassembling the sleeve.

(4) The pressurizing method is pulse electric current sintering in which uniaxial pressing is performed while applying heat and direct current pulse voltage to the hot press die.

  By applying a direct current pulse voltage, the interface of the R-Fe-B based porous magnet particles is activated to promote sintering.

  The hot press mold of the sintered magnet of R-Fe-B system of the present invention for solving the above-mentioned subject is the contents of the following.

(5) A graphite-made hot-pressing mold made of a sintered magnet of R-Fe-B-based sintered magnet for applying pressure while heating R-Fe-B-based porous magnet, wherein the hot-pressing mold is a die And a punch, the die having a C / C composite ring disposed on the outside.

(6) A hot-pressing mold for an R-Fe-B-based sintered magnet, which is pressurized while heating a porous R-Fe-B-based magnet, wherein the hot-pressing mold is a C / C composite A die made of material and a punch made of graphite are provided.

  In addition, it is desirable that the mold for the hot press of the R-Fe-B based sintered magnet of the present invention be in the following mode.

(7) The die has a tapered inner surface and has a sleeve formed of a plurality of divided graphite pieces inside.

According to the method for producing a sintered magnet of R-Fe-B system of the present invention, the die has a ring made of C / C composite material. For this reason, compared with the case where a die | dye is comprised only with graphite, a dice | dies can be miniaturized and heat capacity can be made small.
Therefore, the time required for heating and cooling can be shortened, and melting and deterioration of the R-Fe-B based porous magnet can be prevented.
In addition, since the heat capacity of the die is small, it is easy to control, and if heating is stopped, the temperature rise is easily stopped, and it is possible to prevent the R-Fe-B based porous magnet from being overheated.

It is a perspective view of the type | mold for hot presses of Embodiment 1 of this invention. It is a perspective view of the type | mold for hot presses of Embodiment 2 of this invention. It is a perspective view of the type | mold for hot presses of Embodiment 3 of this invention. It is a perspective view of the type | mold for hot presses of Embodiment 4 of this invention. It is sectional drawing of the type | mold for hot presses of Embodiment 3 of this invention.

(Detailed Description of the Invention)
The method for producing an R-Fe-B-based sintered magnet of the present invention for solving the above problems is characterized in that the R-Fe-B-based porous magnet is placed in a graphite-made hot press mold and heated while being heated. A method of manufacturing a sintered R-Fe-B based magnet according to the present invention, wherein the mold for hot pressing comprises a die and a punch, and the die is a ring made of C / C composite material disposed on the outside. Have.

According to the method for producing a sintered magnet of R-Fe-B system of the present invention, the die has a ring made of C / C composite material. Usually, the C / C composite material has a tensile strength of about 5 to 10 times that of graphite. By arranging the C / C composite ring on the outside of the die, the die can be miniaturized and the heat capacity can be reduced as compared with the case where the die is made of only graphite.
Therefore, the time required for heating and cooling can be shortened, and melting and deterioration of the R-Fe-B based porous magnet can be prevented.
In addition, since the heat capacity of the die is small, it is easy to control, and if heating is stopped, the temperature rise is easily stopped, and it is possible to prevent the R-Fe-B based porous magnet from being overheated.

  A method of producing a sintered R-Fe-B based magnet, wherein an R-Fe-B based porous magnet is disposed in a hot press die and pressed while heating, wherein the hot press die is C / C. It is equipped with a C composite die and a graphite punch.

According to the method of manufacturing a sintered magnet of R-Fe-B system of the present invention, the die is made of C / C composite material. Usually, the C / C composite material has a tensile strength of about 5 to 10 times that of graphite. For this reason, compared with the case where a dice | dies is comprised with graphite, a dice | dies can be miniaturized and heat capacity can be made small.
Therefore, the time required for heating and cooling can be shortened, and melting and deterioration of the R-Fe-B based porous magnet can be prevented.
In addition, since the heat capacity of the die is small, it is easy to control, and if heating is stopped, the temperature rise is easily stopped, and it is possible to prevent the R-Fe-B based porous magnet from being overheated.

  Moreover, as for the manufacturing method of the sintered magnet of R-Fe-B system of this invention, it is desirable that it is the following aspect.

  The die has a tapered inner surface and has a sleeve formed of a plurality of divided graphite pieces inside.

  If a sleeve is provided inside the die, the sintered magnet can be easily removed by disassembling the sleeve.

  The pressurizing method is pulse electric current sintering in which uniaxial pressing is performed while applying heat and direct current pulse voltage to the hot press die.

  By applying a direct current pulse voltage, the interface of the R-Fe-B based porous magnet particles is activated to promote sintering.

  A mold for hot pressing a sintered magnet of R-Fe-B system according to the present invention for solving the above-mentioned problems,

  A graphite-made hot-pressing mold made of a sintered magnet of R-Fe-B-based sintered magnet for applying pressure while heating R-Fe-B-based porous magnet, wherein the hot-pressing mold comprises a die and a punch And the die has a C / C composite ring disposed on the outside.

  A hot press mold for an R-Fe-B sintered magnet, which is pressurized while heating an R-Fe-B porous magnet, wherein the hot press mold is made of a C / C composite material. It has a die and a punch made of graphite.

  In addition, it is desirable that the mold for the hot press of the R-Fe-B based sintered magnet of the present invention be in the following mode.

  The die has a tapered inner surface and has a sleeve formed of a plurality of divided graphite pieces inside.

(Form for carrying out the invention)
FIG. 1 is a perspective view of a hot press according to a first embodiment of the present invention. One embodiment of a method of manufacturing an R-Fe-B sintered magnet will be described with reference to FIG.

  The graphite hot press die 1 is provided with a punch 2 and a die 3. The hot press die 1 is housed in the chamber of the hot press apparatus, and heated and pressed by the upper and lower punches 2 of the R-Fe-B based porous magnet 4 loaded (disposed) in the die 3 A sintered magnet of R-Fe-B type is manufactured.

The punch 2 has a substantially cylindrical shape, and the die 3 is a substantially cylindrical mold having an opening 5 at the center. R-Fe-B based porous magnet 4 is loaded into the opening 5. For example, the die 3 is heated to raise the temperature of the R-Fe-B based porous magnet 4 from 600 ° C to 900 ° C. The porous magnet 4 is pressurized with the punch 2 at a pressure of 1 to 3.0 ton / cm ^{2 to} produce an R-Fe-B based sintered magnet. The punch 2 and the die 3 are preferably made of, for example, carbon, SiC, tungsten carbide or the like which can withstand heating temperature and applied pressure.
In addition, it is preferable that a hole for temperature measurement be formed in the die. Because temperature measurement can be performed near the porous magnet to be heated, the temperature can be accurately controlled.

  The pressing direction of the punch 2 is the pressing axis direction, which is shown as the Z axis in FIG. In addition, although the vertical direction perpendicular to the pressing axis is the X axis or the Y axis, the direction perpendicular to the pressing axis direction is established in all directions around the pressing axis. The lower punch 2 has a buttocks, and the die 3 does not drop when the die 3 is set.

  In the first embodiment, a ring 6 made of a C / C composite material is disposed outside the die 3. The ring 6 is a composite material composed of carbon fibers and a matrix of carbon. Further, the “outside” means that it is on the outside of the die 3 as viewed from the R-Fe-B based porous magnet 4 pressurized in the pressing axial direction (Z axis).

  The inner side of the ring 6 may be, for example, a simple bulk graphite material. A ring 6 made of C / C composite material may be wound around the bulk, and the ring 6 formed separately may be fitted to the outside of the bulk (die 3). The ring 6 made of a C / C composite material can increase the strength even with the same size, thereby enabling downsizing, reducing the heat capacity, and also facilitating temperature control because the overall shape is small. The C / C composite material constituting the ring is not particularly limited and may be any one, but is preferably a filament wound C / C composite material produced by winding carbon fibers.

  Further, if the pressurizing method is pulse electric current sintering in which uniaxial pressing is performed while applying a direct current pulse voltage by the direct current application device 7, a direct current pulse voltage can be applied, and the R-Fe-B based porous magnet 4 The interface of the particles is activated and sintering is promoted. As such a pressurization method, SPS (Spark Plasma Sintering) is mentioned, for example.

  FIG. 2 is a perspective view of a hot press according to a second embodiment of the present invention. Embodiment 2 of the hot press die will be described with reference to FIG.

  In the second embodiment, the die 3 is made of a C / C composite material, and the punch 2 is made of graphite. Usually, the C / C composite material has a tensile strength of about 5 to 10 times that of graphite. Therefore, the die 3 can be miniaturized and the heat capacity can be reduced as compared with the case where the die 3 is made of graphite. Therefore, the time required for heating and cooling can be shortened, and melting and deterioration of the R-Fe-B based porous magnet 4 can be prevented. In addition, since the heat capacity of the die 3 is small, it is easy to control, and if heating is stopped, the temperature rise is easily stopped, and it is possible to prevent the R-Fe-B based porous magnet 4 from being overheated.

  Further, as in the first embodiment, in the pressure application method, pulse current sintering is performed in which uniaxial pressure is applied while applying a direct current pulse voltage by the direct current application device 7. A direct current pulse voltage can be applied, and the interface of the particles of the R-Fe-B based porous magnet 4 is activated to promote sintering.

  FIG. 3 is a perspective view of a hot press according to a third embodiment of the present invention. Embodiment 3 of the hot press die will be described with reference to FIG.

  Embodiment 3 arrange | positions the sleeve 8 which consists of a graphite piece divided | segmented into plurality in the opening part 5 of the dice | dies 3 of Embodiment 1. As shown in FIG. By placing the sleeve 8 at a position facing the R-Fe-B based porous magnet 4 on the inner side of the die 3, the sintered R-Fe-B based sintered magnet is used as a sleeve. It can be easily taken out together. Also, the sleeve 8 may be replaced each time a sintered magnet of R-Fe-B system is manufactured.

  FIG. 4 is a perspective view of a hot press according to a fourth embodiment of the present invention. Embodiment 4 of the hot press die will be described with reference to FIG.

  Embodiment 4 arrange | positions the sleeve 8 which consists of a graphite piece divided | segmented into plurality in the opening part 5 of the dice | dies 3 of Embodiment 2. FIG. By arranging the sleeve 8, it is possible to easily take out the R-Fe-B based sintered magnet together with the sleeve. Also, the sleeve 8 may be replaced each time a sintered magnet of R-Fe-B system is manufactured.

  FIG. 5 is a cross-sectional view of a hot press according to a third embodiment of the present invention. The cross-sectional structure of the hot press die will be described with reference to FIG.

  In the cross section of the hot press die 1, the opening 5 of the die 3 is tapered, and the outer surface is tapered when viewed from the R-Fe-B porous magnet 4. Further, along the tapered shape of the opening 5, a sleeve 8 having a tapered outer surface and made of a plurality of divided graphite pieces is disposed. By forming the opening 5 and the outer surface of the sleeve 8 in a tapered shape, the R-Fe-B sintered magnet can be easily taken out of the die 3 together with the sleeve 8. That the inner surface of the opening 5 and the outer surface of the sleeve 8 have a tapered shape is not limited to the third embodiment, and is applicable to all of the first, second, and fourth embodiments. Illustration of the buttocks of the lower punch 2 is omitted.

  The present invention is not limited to the embodiments described above, and appropriate modifications, improvements, etc. are possible. In addition, the materials, shapes, dimensions, numerical values, forms, numbers, locations, etc. of the respective components in the above-described embodiment are arbitrary and not limited as long as the present invention can be achieved.

  The method for producing a sintered magnet of the present invention and the mold for hot pressing are compatible with fields such as production of a sintered magnet of R-Fe-B based on which the temperature and time of sintering can be easily controlled and strong magnetic force can be obtained. It is possible.

DESCRIPTION OF SYMBOLS 1 type for hot press 2 punch 3 die 4 porous magnet of R-Fe-B system 5 opening 6 ring made of C / C composite 7 direct current application device 8 sleeve

Claims (7)

A method for producing a sintered R-Fe-B magnet, which comprises placing an R-Fe-B-based porous magnet in a graphite-made hot press mold and pressing it while heating,
The hot press mold comprises a die and a punch,
The method for manufacturing a sintered R-Fe-B magnet having a C / C composite ring disposed on the outside of the die. A method of manufacturing a sintered R-Fe-B-based magnet, comprising placing an R-Fe-B-based porous magnet in a hot press mold and pressing it while heating,
The said hot press type | mold is a manufacturing method of the sintered magnet of R-Fe-B type | system | group provided with the dice | dies made from C / C composite material, and the punch made from graphite.   The method for manufacturing an R-Fe-B based sintered magnet according to claim 1 or 2, wherein the die has a tapered inner surface and has a sleeve formed of a plurality of divided graphite pieces inside.   The R-Fe-B system according to any one of claims 1 to 3, wherein the pressurizing method is pulse electric current sintering in which uniaxial pressing is performed while applying heat and direct current pulse voltage to the hot press die. Method of manufacturing a sintered magnet Graphite-based hot-pressing mold for an R-Fe-B-based sintered magnet that is pressurized while heating an R-Fe-B-based porous magnet,
The hot press mold comprises a die and a punch,
The die for the R-Fe-B sintered magnet having a C / C composite ring disposed on the outer side thereof. It is a mold for hot pressing of a sintered magnet of R-Fe-B system which applies pressure while heating a porous magnet of R-Fe-B system,
The said hot press type | mold is a hot press type | mold of the sintered magnet of R-Fe-B type | system | group provided with the dice | dies made from C / C composite material, and the punch made from graphite.   The R-Fe-B sintered magnet according to claim 5 or 6, wherein the die has a tapered inner surface and has a sleeve formed of a plurality of divided graphite pieces inside.

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